Ski having tensioning means



Dec. 22, 1959 F. rAvl 2,918,293

SKI HAVING TENSIONING MEANS Filed Oct. 24, 1957 FIG. l.l @3+ /4 45 3,7

4Z /Z y4//5 ij i FIG. 2.

FIG. 3. FIG. 8

.1 jj /4 /562 f,

United States Patent O SKI HAVING TENsIoNlNG MEANS i Felix ravi, New York, N.Y. Application October 24, 1957, Serial No. 692,124 `4 claims. (ci. 28o-11.13)

This invention relates to skis and more particularly to skis variable at will in stiffness and camber.

One object of the invention is to provide a means for varying the stiffness of skis.

Another object is to provide means for varying the camber of the ski.

Still another object is to provide a means for securing continuous steel edge-strips to the ski and which strips will not work loose or buckle when the camber of the ski is varied.

Another object is to provide a'ski of laminated construction in which the laminations are drawn more tightly together as the ski is excessively flexed, as in accidents.

Another object is to provide a ski in which continuous steel edge-strips may be easily replaced if they become damaged.

Another object is to increase the strength of a ski.

And yet another object is tol minimize vibration of the ski.,

Still another object is to provide means for varying the stiffness of the ski which means will be light in weight, noncumbersome, and will not interfere with boot fastenings or bindings, or protrude to gather snow or become` caught on objects nearby.

The inventive features for the attainment of these and other objects are shown in connection with a ski having at least one recess, hole, or raceway extending the substantial length thereof with a tension member secured at one' end and having means at the other to alter the effective length of the member with respect to the ski to cause the ski to bow. Yieldable means are provided for mounting steel edge strips on the bottom of the ski.

In the accompanying drawing showing, by way of example, several of many possible embodiments of the invention,

Fig. l is a transverse cross section of the ski;

Fig. 2 is a diagrammatic representation of the ski as seen from the side showing the tension members;

Fig. 3 is` a fragmental longitudinal sectional view of the ski;

Figs. 4 and 5 show details of the front and rear ends of the ski;`

Fig. 6 is a fragmental sectional longitudinal view showing means for mounting the edge strips;

Fig. 7 shows a modification of the invention;

Fig.f8` shows another modification of the invention, and

` Fig. 9 shows the spacing ofthe means for securing the edge strips of the ski. Y The skicomprises a longitudinal wooden strip`10 fortning the body of the ski and having upper and lower faces 11 and 12. The strip may be solid but preferably is built up from strip elements 14 secured together by adhesive. The lower face 12 is provided with a pair of substantially parallel grooves, one in each lateral portion 16 of the strip and substantially the length thereof.

A tube 18 of yieldable metal such as aluminum is disposed inr each groove and extends substantially the ICC length thereof. A wire 19 in each tube is secured at its forward end 20 against rotation and rearward movement relative to the forward end 21 of the ski body by being made fast to a toe-piece 22. The rear end 24 of the wire projects rearwardly of the rear end 25 of the tube and strip and is provided with threads 26. The rear end 24 passes through an abutment plate 29 against the rear end 28 of the strip, the plate being provided with holes 30 for allowing the wire rearl ends to extend rearwardly of the plate. A long nut 31 is provided on each wire rear end for engagement against the abut ment plate, to draw up on the wires and put the strip under compression along the under portion thereof.

A resilient aluminum alloy top sheet 32 is disposed over said upper face and bonded thereto, and a similar lower sheet 34 over the lower face and bonded thereto, covers the grooves 15. Stainless steel edge-strips 35 having an exposed outer and lower edge 36 are disposed against the lower face of the lower sheet at the marginal portions 16 of the sheet and wooden strip and for substantially the length thereof. The edge strips are secured to the ski body by screws 38 passing through provided holes 37 in the upper sheet, Wooden strip, and lower sheet and in fast threaded engagement with the edgestrips, the screws being flush with the lower face 39 of the edge-strips. The holes toward each end of the ski have oval cross section with an increasing major axis as at 40 (Fig. 6) parallel with the direction of the strip as the section is taken from the upper to the lower sheets to permit longitudinal slippage of the edge-strips when the ski is exed.

A runner sheet 41 of plastic is secured to the lower face of the lower sheet between the edge-'strips and flush therewith. The lower face of the ski may be provided with a median groove 42.

Suitable front and rear caps 44 and 45, shaped so as not to interfere with normal skiing may be provided to give the ski a finished appearance.

While the invention as shown in Fig. 1 is preferable, the grooving at 15 may be replaced by bores 15a (Fig. 7) particularly if the ordinary wooden-type ski is desired. The provision of such bores is no great problem since the elements 14 need only be grooved before assembly and the tubing 18 inserted before the elements are bonded together. ln fact, in the construction of the invention of Fig. l resin or plastic is used for bonding the lower sheet 34 to the body and the resin enters the grooves 15 about the pre-disposed tubes. Nor is it necessary that the bores or grooves always be in the lower portion of the ski; at least a portion of the bore may be in the upper portion as in Fig. 8. This Fig. 8 is included `to show that the bore may be intermediate the marginal portions 16. Combinations of various positions may be used so as to compensate for warp and to concentrate camber in different locations along the ski.

The aluminum alloy sheets 32, 34 are preferably of aircraft aluminum alloy 7075-T6 of the order of a few hundredths of an inch thick, say 0.03. This material has elasticity and will stretch and retract with the wood. Prior to bonding it to wood it is advisable to give the sheet a primer treatment with casein-latex emulsion to insure a good bond. Suitable commercial adhesives may be used to make the bond. The runner sheet 41 may be of suitable material already in use for the purpose, such as pyroxylin. Sun glare reiiected from the upper cover sheet may be prevented by a covering 48 of, say, plastic.

The wires are of the order of .09 inch in diameter, and fit fairly well in the aluminum tubing without vibration. Tension on the wires is varied by turning the nuts 31, the threading of which is preferably line so as to obtain close adjustment, lessen twisting of the wires and reduce tendency for the nut to work loose. The latter condition can be avoided by having the cap 45 provided with a hole 49 to provide frictional engagement with the nut.

When the wires are drawn up the camber of the ski is increased with a corresponding amount of slippage between the edge-strips 35 and the ski body 10 and lower sheet 34, the body and sheet -being substantially integral.

It is preferable that the slippage be divided between each end E of the ski, for in practice the total slippage may amount to as much as 3A inch in a 6 foot ski, or

3/16 at each end. Accordingly, screws in the mid-portionA M of the ski (Fig. 9) pass through cylindrical holes in the wood and lower cover to fasten the edge-strips securely, while toward each end E the hole flares toward the bottom as in Fig. 6 longitudinally of the ski but not transversely thereof. The cross section is, substantially the entire length, the same as in Fig. 1.

The screws 38 are case hardened and self tapping so that the screw becomes almost integral with the stainless steel edge-strip, but the yieldability of the screw, and to some extent of the strip, permits the required slippage.

The screws 3S also have the function of binding the aluminum sheets more tightly to the wood when the ski is excessively llexed as in accidents. In most ski constructions the aluminum sheets become separated from the wood during great flexing. An inspection of Fig. 6 shows that flexing, with slippage of the steel strips 35, tends to draw the laminations of the ski closer together except for the thin plastic layer 48.

A ski has a tendency to chatter or vibrate in use on certain types of snow. In the present ski this vibration is appreciably dampened by the rubbing of the edge strip on the lower cover sheet 34 so that the energy normally present to sustain the vibration is dissipated as frictional heat.

The loss in strength of the wood due to the grooves or bores 15a is more than counterbalanced by the steel edge-strips 35 and wires.

The present invention does not interfere with boot binders, is light, permits a wide range of adjustment and leaves the ski with a conventional appearance.

The wood may be of a type used for conventional skis.

Still other modications may be made by those skilled in the art, for instance the strip 35 vmay be omitted if the wood has sufficient strength. Of course the wire must normally lie remote from the plane of flexure of the ski.

The 'invention claimed is:

'1. A ski comprising a longitudinal strip forming the body of the ski and having upper and lower faces and an upturned forward end portion; an end piece substantially across the forward end of the body; the body being provided With a pair of substantially parallel bores, one in each lateral portion of the strip and substantially the length thereof and nearer the lower face than the upper face; a wire in each bore and secured fast to the said end piece, the rear end of the wire projecting rearwardly of the rear end of the strip and provided with threads; abutment means against the rear end of the strip and provided with holes for allowing the wire rear ends to extend rearwardly of the abutment means, and a nut on the end of each of the wires for engaging the abutment means and tightening the wires to cause the body to bow.

2. A ski comprising a longitudinal wooden strip forming the body of the ski and having upper and lower faces and an upturned lforward end portion; an end piece substantially across the forward end of the body; the lower face being provided with a pair of substantially parallel grooves, one in each lateral portion of the strip and substantially the length thereof; a tube in each groove and extending substantially the length thereof; a wire in each tube and secured fast to the said end piece, the rear end of the wire projecting rearwardly of the rear end of the tube and strip and provided with threads; an abutment plate against the rear end of the strip and provided with holes for allowing the wire rear ends to extend rearwardly of the plate; and a nut on the end of each of the rear ends of the wire and engaged against the plate.

3. A ski comprising a longitudinal wooden strip forming the body of the ski and having upper and lower faces and an upturned forward end portion; an end piece substantially across the-forward end of the body; the lower facev being provided with a pair of substantially parallel grooves, one in each lateral portion of the strip and substantially the length thereof; a tube in each groove and extending substantially the length thereof; a wire in each tube and secured fast to the said end piece, the rear end of the wire projecting rearwardly of the rear end of the tube and strip -and provided with threads; an abutment plate against the rear end of the strip and provided with holes for allowing the wire rear ends to extend rearwardly of the plate; a long nut on each wire rear end for engagement against the abutment plate, a resilient aluminum alloy top sheet over said upper face and bonded thereto, and a similar lower sheet over the lower face and bonded thereto and covering the grooves; a pair of steel edge-strips, each having an exposed outer and lower edge, disposed against the lower face of the lower sheet at the marginal portions of the sheet and wooden strip and substantially the length thereof; screws passing through provided holes in the upper sheet wooden strip and lower sheet and in fast threaded engagement with the edge-strips, the screws being ush with the lower face of the edge-strips, the holes toward each end of the ski having ovaly cross section with an increasing major axis parallel with the direction of the strip as the section Vis taken from the upper to the lower sheets to permit longitudinal slippage of the edge-strips when the ski is liexed; and a runner sheet of plastic secured to the lower face of the lower sheet between the edge-strips and flush therewith.

4. A ski as claimed in claim 3, the edge-strips being secured fast to the body at the mid portion thereof.

References Cited in the le of this patent UNITED STATES PATENTS 363,074 Lockwood May 17, 1887 1,579,285 Danaher et al. Apr. 6, 1926 2,188,582 Serr Jan. 30, 1940 2,795,431 Metcalfe et al. June 11, 1957 FOREIGN PATENTS 140,270 Austria Jan. 25, 1935 927,897 France May 19, 1947 194,210 Switzerland Feb. 16, 1938 1,128,309 France Aug. 20, 1956 

